Figure 1 - uploaded by Phyo K Myint
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Catheter arteriography (DSA) showing clot (embolus) at the top of the basilar artery and persistent foetal trigeminal artery providing main supply to basilar artery.
Source publication
We report a case of bilateral thalamic infarct associated with bilateral eyelid apraxia. This extremely rare condition provides
us with an opportunity to map clinical and neuroimaging findings to help better understand brain function.
Citations
... Myint et al.2 reported a case of ALO in isolated bilateral thalamic infarction, suggesting that the paramedian thalamic nuclei may have a role in the voluntary eyelid movements network. ...
Aim: The aim of this study is to analyze the incidence, etiology, symptoms, diagnostic process and treatment of bilateral thalamic infarct on the basis of our own experience. Case series: Five cases of bilateral paramedian thalamic stroke with different clinical manifestations are presented. In two patients the presence of artery of Percheron was detected. Comment: The bilateral thalamic infarct is an unusual and rare type of ischemic stroke. Due to the variety of symptoms, it may be difficult to diagnose without MR imaging. Symptoms may be transient, but frequently a persistent neurological deficit is observed. The thalamus is the “centre” for all impulses reaching the brain. It is involved in cognitive functions, emotional and motor responses. Therefore, impaired consciousness and behavioral changes are the main symptoms of thalamic stroke.
Bilateral thalamic infarctions are rare and usually caused by vascular occlusions. When symptomatic, it is important to make a distinction between different vascular etiologies in order to provide an effective and timely therapeutic response. Clinical presentations may not adequately differentiate between the vascular etiologies alone. It is therefore important to use imaging technologies to distinguish appropriately the origin of the infarct so that proper treatment can be administered. Advanced imaging techniques, such as CT angiography and MR angiography, have proved useful for distinguishing between arterial and venous causes of bithalamic infarctions. Bilateral thalamic venous infarctions can be treated with anticoagulation medication and with thrombolysis in more severe cases. Bilateral thalamic arterial infarctions may be treated with thrombolysis.
Carotid-vertebrobasilar anastomoses-the trigeminal, otic, hypoglossal, and proatlantal intersegmental arteries-serve as transitory channels between primitive internal carotid arteries and bilateral longitudinal neural arterial plexus, which is the precursor of future basilar artery, when the human embryo reaches about 4-mm length.
Normal and/or abnormal morphofunctional aspects of the prenatal and postnatal forms of the trigeminal artery are described according to personal and literature data. Many arteries of similar origin and course are also noted in the differential diagnosis of the trigeminal artery.
The persistent primitive trigeminal artery, as the most commonly carotid-vertebrobasilar anastomosis, has a reported incidence of 0.03-2.2% in the literature. There is female sex predilection, and it may be discovered in patients of any age, on either side, and in association with many vascular variants. Although the significance of persistent primitive trigeminal artery regarding the development of an aneurysm or association with another pathological condition may not be clear, its (ab)normal morphology is the inspiration for anatomists, especially for neurosurgeons, before planning diagnostic and therapeutic procedures.
Synchronous bilateral paramedian thalamic stroke (SBPTS), usually equated to Percheron artery infarction, is considered to be uncommon and difficult to diagnose clinically. Its characterization is based on the original description plus a few small series.
To characterize SBPTS clinically by collecting cases and identifying the key difficulties for an early diagnosis.
Six cases at our centre plus another 115 located by systematic literature search and critical reading of articles fulfilled the criteria for SBPTS. An analysis was made of the variables age, gender, vascular risk factors, aetiology, alterations and fluctuations of consciousness, need for intubation, cognitive-behavioural disorders, pupillary changes, other neurological focal disorders and brainstem involvement on imaging studies.
Of note in our series were disorders of consciousness (n=5), their fluctuations (n=3) and the diagnostic delay (seven days, with MRI in four patients). In only one case was a bilateral thalamic lesion seen on the initial CT. Joint analysis of all the cases showed a mean age of 61 years, a predominance of men (58%), the presence of vascular risk factors in 77%, a mainly cardioembolic aetiology (34% among those that were specified), sensory involvement in 75% (intubation in 7% and fluctuations in 16.5%), cognitive-behavioural disorders in 43%, oculomotor in 73%, pupillary in 31%, other in 67% and specified brainstem lesion in 37%.
The SBPTS syndrome has a variable presentation with a low sensitivity on the initial CT, requiring brain MRI for typification. This explains the diagnostic difficulty and the fact that its frequency is probably underestimated.
Apraxia of eyelid opening is the inability to voluntarily open the eyes in the absence of motor dysfunction or blepharospasm. It has been described mostly in association with extrapyramidal diseases and only rarely in cortical lesions. We report a right-handed woman with a right subcortical lesion due to borderzone infarction showing eyelid opening apraxia.
During the last decades, many studies have shown that the thalamus is crucially involved in language and cognition. We critically reviewed a study corpus of 465 patients with vascular thalamic lesions published in the literature since 1980. 42 out of 465 (9%) cases with isolated thalamic lesions allowed further neurocognitive analysis. On the neurolinguistic level, fluent output (=31/33; 93.9%), normal to mild impairment of repetition (=33/35; 94.3%), mild dysarthria (=8/9; 88.9%) and normal to mild impairment of auditory comprehension (=27/34; 79.4%) were most commonly found in the group of patients with left and bilateral thalamic lesions. The taxonomic label of thalamic aphasia applied to the majority of the patients with left thalamic damage (=7/11; 63.6%) and to one patient with bithalamic lesions (=1/1). On the neuropsychological level, almost 90% of the left thalamic and bithalamic patient group presented with amnestic problems, executive dysfunctions and behaviour and/or mood alterations. In addition, two thirds (2/3) of the patients with bilateral thalamic damage presented with a typical cluster of neurocognitive disturbances consisting of constructional apraxia, anosognosia, desorientation, global intellectual dysfunctioning, amnesia, and executive dysfunctions associated with behaviour and/or mood alterations. Our study supports the long-standing view of a 'lateralised linguistic thalamus' but restates the issue of a 'lateralised cognitive thalamus'. In addition, critical analysis of the available literature supports the view that aphasia following left or bithalamic damage constitutes a prototypical linguistic syndrome.
